Chad's president has increased his army's presence in the country's east, the stronghold of a group of disaffected soldiers bent on overthrowing him. Analysts fear the new rebel movement could signal the expansion into Chad of the war in neighboring Darfur.

Chad's capital Ndjamena is virtually empty of army personnel says journalist Evariste Ngaralbaye.

All heavy equipment, tanks, helicopters, and thousands of soldiers, he says, have been sent to the east. He says there are reports forces are being concentrated in the city of Abeche, near the country's eastern border with Darfur.

The military deployment is being made in an area that has recently become a stronghold of a new armed opposition group called the Platform for Change, National Unity and Democracy, known by its French acronym SCUD.

The group has called for President Idriss Deby to step down, but has offered no political program of its own.

President Deby recently dissolved the Republican Guard - the elite army corps that normally serves to ensure the government's stability. No reason for the decision was given in the decree published on Friday.

But a researcher for U.S.-based Human Rights Watch, Leslie Lesko, says Mr. Deby has had a troubled relationship with his own army since a 2004 attempted mutiny. She says links exist between SCUD and leaders of that insurrection.

"It appears that at least some of the people that are involved in this new rebel group, SCUD may be linked to those mutineers. But there is a lot that is unclear about who this group is and what their agenda is," said Leslie Lesko.

Ms. Lesko says, there are worrying links to the conflict in Sudan's neighboring Darfur region.

Mr. Deby launched a 1990 invasion of Chad from Sudan. The invasion would eventually lead to his seizing the presidency.

Ms. Lesko says the invasion had the consent of the government in Khartoum. But the president's clan, many of whose members hold important positions in Chad's government and military, has ethnic ties with Darfur's rebel groups.

Many members of President Deby's clan, Ms. Lesko says, feel he has not done enough to support the rebels against Sudan's army and the pro-Khartoum janjaweed militia.

"It is clearly a sign of President Deby's fragility. And this is something again that observers of the region of Chad and Darfur have seen coming for some time. For some time, it has been clear that the conflict in Darfur was spilling over into Chad and could have this kind of effect on regional stability," she said.

Other analysts say some high-ranking soldiers would like Mr. Deby to take a harder line against the government in Sudan and may be involved in SCUD, while there is also a risk Sudan could fund a rebellion against Mr. Deby.

Relations between Ndjamena and Khartoum have soured in recent months. Chad has accused janjaweed fighters of staging raids on Chadian villages.

Hundreds of thousands of Darfur refugees, many of them from Mr. Deby's ethnic group, live along the border between the two countries.